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For the last decade, the most influential decision has been that of the House of Lords in Kirin-Amgen, in which Lord Hoffmann said, essentially, that all issues of infringement could be resolved by adopting a 'purposive' construction to the language of the patent claim, so giving effect to "what the person skilled in the art would have understood the patentee to be claiming".

The role of the House of Lords as the highest appeal court has since ended; the Supreme Court of the UK has, since 1 October 2009, been the highest court of appeal for all civil law cases in the UK. Now, in Actavis UK Limited & Ors v Eli Lilly and Company [2017] UKSC 48 (12 July 2017), the leading Justice of the current generation, Lord Neuberger (with the agreement of the other four Justices), respectfully rowed back from Lord Hoffmann's judgment in Kirin-Amgen.

Lord Neuberger went back to first principles, beginning with the legislative provisions, the critical text being that of Article 69 of the European Patent Convention (EPC) and the Protocol on its interpretation.

Article 69(1) EPC states:

"The extent of the protection conferred by a European patent or a European patent application shall be determined by the claims. Nevertheless, the description and drawings shall be used to interpret the claims."

As amended in 2000, the Protocol provides as follows:

"Article 1 General principles

Article 69 should not be interpreted as meaning that the extent of the protection conferred by a European patent is to be understood as that defined by the strict, literal meaning of the wording used in the claims, the description and drawings being employed only for the purpose of resolving an ambiguity found in the claims. Nor should it be taken to mean that the claims serve only as a guideline and that the actual protection conferred may extend to what, from a consideration of the description and drawings by a person skilled in the art, the patent proprietor has contemplated. On the contrary, it is to be interpreted as defining a position between these extremes which combines a fair protection for the patent proprietor with a reasonable degree of legal certainty for third parties.

Article 2 Equivalents

For the purpose of determining the extent of protection conferred by a European patent, due account shall be taken of any element which is equivalent to an element specified in the claims."

This, said Lord Neuberger, meant that ([54]):

"…a problem of infringement is best approached by addressing two issues, each of which is to be considered through the eyes of the notional addressee of the patent in suit, ie the person skilled in the relevant art. Those issues are: (i) does the variant infringe any of the claims as a matter of normal interpretation; and, if not, (ii) does the variant nonetheless infringe because it varies from the invention in a way or ways which is or are immaterial? If the answer to either issue is "yes", there is an infringement; otherwise, there is not."

Lord Neuberger explained that issue (i) self-evidently raises a question of interpretation, whereas issue (ii) raises a question which would normally have to be answered by reference to the facts and expert evidence. The difficulty with Lord Hoffmann's approach in Kirin-Amgen was that it conflated the two issues. This was wrong in principle and, therefore, could lead to error. Issue (ii) involves not merely identifying what the words of a claim would mean in their context to the notional addressee, but also considering the extent if any to which the scope of protection afforded by the claim should extend beyond that meaning.

What is the correct approach?

Lord Neuberger explained that the first question, of whether the variant infringed any of the claims as a matter of normal interpretation, requires the application of the normal principles of interpreting documents. In the UK these were recently affirmed by Lord Hodge in the Supreme Court in Wood v Capita Insurance Services Ltd [2017] UKSC 24 (paragraphs 8 to 15).

The second question poses more difficulties of principle: what is it that makes a variation “immaterial"? In this context, Lord Neuberger considered that the three questions formulated by Hoffmann J (as he then was) in Improver (which pre-dated Kirin-Amgen), provide helpful assistance but needed some reformulation. He proceeded to undertake the reformulation, saying that the reformulated questions remain only guidelines, not strict rules, and that they may also sometimes have to be adapted to apply more aptly to the specific facts of a particular case. The reformulated questions are:

Notwithstanding that it is not within the literal meaning of the relevant claim(s) of the patent, does the variant achieve substantially the same result in substantially the same way as the invention, ie the inventive concept revealed by the patent?

Would it be obvious to the person skilled in the art, reading the patent at the priority date, but knowing that the variant achieves substantially the same result as the invention, that it does so in substantially the same way as the invention?

Would such a reader of the patent have concluded that the patentee nonetheless intended that strict compliance with the literal meaning of the relevant claim(s) of the patent was an essential requirement of the invention?

Lord Neuberger clarified:

"In order to establish infringement in a case where there is no literal infringement, a patentee would have to establish that the answer to the first two questions was "yes" and that the answer to the third question was "no"."

For those familiar with Hoffmann J's Improver questions, Lord Neuberger's reasoning in paragraphs [59]-[65] of his judgment is worth reading in full, for its detail of how and why the tests have been developed. His analysis indicates where Hoffmann J's reasoning "may" have gone wrong in the Improver case, with the result that the device incorporating a rubber rod instead of a "coiled helical spring" was found not to infringe in the UK although it was found by the German, Italian and Dutch courts to infringe.

The law on recourse to the prosecution history

In support of its case on (non) infringement, Actavis relied upon the prosecution history of the patent. This gave rise to a question of general application: whether, and if so when, is it permissible to have recourse to the prosecution of a patent when considering whether a variant infringes that patent?

Lord Neuberger concluded as follows ([87]-[88]):

"In my judgment, it is appropriate for the UK courts to adopt a sceptical, but not absolutist, attitude to a suggestion that the contents of the prosecution file of a patent should be referred to when considering a question of interpretation or infringement, along substantially the same lines as the German and Dutch courts. It is tempting to exclude the file on the basis that anyone concerned about, or affected by, a patent should be entitled to rely on its contents without searching other records such as the prosecution file, as a matter of both principle and practicality. However, given that the contents of the file are publicly available (by virtue of article 128 EPC 2000) and (at least according to what we were told) are unlikely to be extensive, there will be occasions when justice may fairly be said to require reference to be made to the contents of the file. However, not least in the light of the wording of article 69 EPC 2000…the circumstances in which a court can rely on the prosecution history to determine the extent of protection or scope of a patent must be limited.

While it would be arrogant to exclude the existence of any other circumstances, my current view is that reference to the file would only be appropriate where (i) the point at issue is truly unclear if one confines oneself to the specification and claims of the patent, and the contents of the file unambiguously resolve the point, or (ii) it would be contrary to the public interest for the contents of the file to be ignored. The first type of circumstance is, I hope, self-explanatory; the second would be exemplified by a case where the patentee had made it clear to the EPO that he was not seeking to contend that his patent, if granted, would extend its scope to the sort of variant which he now claims infringes.

The relevant claims of Eli Lilly's European patent number 1,313,508, for the purposes of the present dispute, were claims 1 and 12, but the court's reasoning focused on claim 1. Claim 12 was in purpose limited product form; Claim 1 was in "Swiss form", in the following terms:

"1. Use of pemetrexed disodium in the manufacture of a medicament for use in combination therapy for inhibiting tumour growth in mammals wherein said medicament is to be administered in combination with vitamin B12 or a pharmaceutical derivative thereof [which it then specifies]."

The specification of the patent described the invention as concerned with the reduction of toxicity associated with antifolates by their administration with a methylmalonic acid lowering agent as vitamin B12. Several antifolates were specifically identified as in development and pemetrexed disodium was expressly described.

Actavis's proposed products involved pemetrexed compounds being used together with vitamin B12 for cancer treatment. However, rather than pemetrexed disodium, the active ingredient in those products ("the Actavis products") was (a) pemetrexed diacid, (b) pemetrexed ditromethamine, or (c) pemetrexed dipotassium.

The Actavis products did not infringe on the basis of a normal interpretation of claim 1. However, Lord Neuberger concluded that they all involved a medicament containing the pemetrexed anion and vitamin B12, and achieved substantially the same result in substantially the same way as the invention. Once he or she knew that the Actavis products achieved substantially the same result as the invention, the notional addressee of the patent would have thought it obvious that this was so, particularly as he or she would have regarded investigating whether pemetrexed free acid, pemetrexed ditromethamine or pemetrexed dipotassium worked as a routine exercise. On the third question, the Court of Appeal had placed too much weight on the words of the claim. It was very unlikely that the notional addressee would have concluded that the patentee could have intended to exclude any pemetrexed salts other than pemetrexed disodium from the scope of protection.

He then turned to the prosecution history. The examiner had rejected claims using "antifolate" terminology for reasons of disclosure and clarity (Articles 83 & 84 EPC). In response, Lilly proposed amended claims using the word "pemetrexed". The examiner objected to these claims on the basis of added matter (Article 123(2) EPC), saying there was no basis for such terminology because pemetrexed was a distinct compound from pemetrexed disodium. Reserving its position, Lilly filed new claims using "pemetrexed disodium" wording and the application proceeded to grant.

Lord Neuberger said that, although it was unnecessary to decide the issue, in his view the examiner was wrong to take the view that the patent should be limited to pemetrexed disodium because the teaching of the patent did not expressly extend to any other antifolates. However, even if the examiner was right or at least justified in taking the stance that he did, this did not have any bearing on the question of whether any pemetrexed salts other than pemetrexed disodium should be within the scope of the patent pursuant to the doctrine of equivalents. Lord Neuberger said ([89]):

"The whole point of the doctrine is that it entitles a patentee to contend that the scope of protection afforded by the patent extends beyond the ambit of its claims as construed according to normal principles of interpretation."

So the contents of the prosecution file did not justify departing from the preliminary conclusion that the Actavis products directly infringed claim 1.

Lord Neuberger then considered the issue of whether the French, Spanish and Italian designations of the patent were directly infringed, again concluding, contrary to the Court of Appeal and Arnold J, that they were. The detailed reasoning is contained in paragraphs 92-102 of the judgment.

The expression "pemetrexed disodium" was not limited to the solid, or crystalline, chemical. Accordingly, even if pemetrexed dipotassium would not of itself infringe if it was administered with vitamin B12, at least provided that the ratio of sodium ions to pemetrexed ions was at least 2:1, there would be infringement when it was administered in saline solution, because the solution would contain pemetrexed disodium.

Again, the UK court's conclusions were considered to apply equally to France, Italy and Spain.

Comment

The UK Supreme Court's judgment in Actavis v Eli Lilly marks the most significant development in UK patent law for decades.

Apparently aligning the UK law of infringement more closely with that of Germany, the (re-) introduction of a doctrine of equivalents can be expected to assist patent proprietors in defending their monopoly against immaterial variants, to reduce the incidence of inconsistent conclusions on infringement as between the courts of the UK and those of other major EPC jurisdictions, and to smooth the way for the harmonisation of the law regarding infringement expected with the coming into force of the Unified Patent Court.

Also importantly for patentees, the existence of a doctrine of equivalents potentially provides greater wriggle room, when seeking an effective and meaningful scope of protection which is also justified by the level and scope of the invention disclosed.

The UK Supreme Court's decision is one, therefore, that should be considered without delay by inventors, patent attorneys, litigators and potential infringers alike.